A number of different compositions and methods have been proposed for preparing bleaching, cleaning, disinfecting and sanitizing solutions. These include compositions containing available chlorine such as various solid hypochlorite and chloramine compositions which can be employed as granules, but are more commonly employed as tablets.
In order to act effectively as a sanitizing agent, it is desired that the composition disintegrate quickly to form hypochlorous acid or hypochlorite ions. Solid hypochlorite compositions include alkali metal hypochlorites such as lithium hypochlorite as well as alkaline earth hypochlorites, for example, calcium hypochlorite and dibasic magnesium hypochlorite.
Chloramine compositions which are suitable include solid chloroisocyanurate compositions, i.e., those containing trichloroisocyanuric acid, dichloroisocyanuric acid, salts of dichloroisocyanuric acid such as alkali metal dichloroisocyanurates and alkaline earth metal dichloroisocyanurates as well as complexes and mixtures thereof.
Tablets having a high proportion of a chloramine composition such as trichloroisocyanuric acid or dichloroisocyanuric acid or its alkali salts have the disadvantage that they dissolve relatively slowly in cold water. It is known to include in these chloramine tablets additives such alkali metal carbonates or bicarbonates and solid organic acids as disintegration agents. When water is added, carbon dioxide is freed which encourages the disintegration and dissolution of the tablets. While tablets including these additives dissolve rapidly in warm water, their rate of dissolution in cold water is not substantially greater than that of dichloroisocyanuric acid or its alkali metal salts.
South African patent No. 73-9740, issued to Henkel & Cie teaches making readily soluble tablets by mixing dichloroisocyanuric acid or its alkali metal salts with starches such as potato, maize, wheat or rice starch, or starches which have been chemically partially reduced, peptized, or carboxymethylated. These tablets are used for the production of bleaching and disinfecting solutions, for example, for textiles, cleansing and rinsing preparations, alkaline bottle cleaners and mechanical dish washer preparations. The tablets can contain from 2.5 to 18 percent by weight of the starch and 80-97 percent by weight of sodium or potassium dichloroisocyanurate. While the addition of a starch does increase the rate of solubility of the tablets, the resulting solutions are not clear.